1. Field of the Invention
This invention relates generally to drive surface configurations of the type which are commonly used with driving elements, such as wrenching members.
2. Description of the Prior Art
There are many types of known drive elements for driving associated fasteners or other driven members. For example, one common type of drive element is a wrench, which may have a handle, with a wrenching head at either or both ends. Another common type of drive element is a socket tool for use with associated handle or lever members. Each such drive element typically has at least two drive surfaces which are dimensioned and arranged for engagement, respectively, with corresponding flat sides of an associated fastener or other driven member of appropriate size. The driving surfaces are commonly smooth planar surfaces.
A disadvantage of such a driving element is the inadequate gripping force between the driving surfaces and the associated driven member. As a result, the driving element may have a tendency to slip off the driven member when torque is applied thereto. Also, it increases stress in the associated driven member and can tend to deform the corners thereof. This tendency to round off the corners of a fastener or other driven member is particularly likely to occur in the off or counterclockwise direction of rotation, since it frequently requires more torque to loosen a tightened fastener, for example, then it does to tighten it.
Heretofore, driving elements have been provided with roughened or high-friction regions on the driving surfaces to improve gripping engagement with the associated driven member. Thus, for example, serrations may be provided along each driving surface. While such serrations can improve overall frictional gripping, they have heretofore provided essentially the same frictional gripping force in either direction of rotation.